Constant velocity joints (CV joints) are common components in vehicles. Constant velocity joints are often employed where transmission of a constant velocity rotary motion is desired or required. CV joints are typically greased or otherwise lubricated for the life of the component. The joints are preferably sealed to retain the grease or lubricant inside the joint while keeping contaminants and foreign matter, such as water and dirt, out of the joint. Moreover, a sealing boot, which may be made of rubber, thermoplastic, silicone material, or the like usually encloses portions of the CV joints (such as an open end). Additionally, the opposite end of the joint may also be enclosed with a grease cover to close off the CV joint from contaminants.
During operation, a CV joint may create excess internal pressures in the inner chamber of the joint. In such instances, it is often desirable to vent pressurized gases from the chamber of the joint to the outer atmosphere to reduce the internal temperature of the joint. This function can prevent undesirable pressure build-up during operation of the joint that could damage or compromise components such as the sealing boot. Consequently, many CV joints include a vent.
Vents may be provided in a grease cover of a CV joint, as an alternative or in addition to one or more vents in a sealing boot. Vents provided in a grease cover are typically effective for venting gases from the interior of the joint during operation of the CV joint. However, grease cover vents also may allow grease or other lubricants to escape the joint interior when gases are vented, particularly during assembly of the CV joint. Hydraulic pressure is typically created within the joint interior when the shaft is installed into the joint. The hydraulic pressure may cause venting of gases from within the joint interior through the grease cover vent and may additionally force some of the grease contained within the joint interior out the vent also.
Accordingly, there is a need in the art for a grease cover vent for a CV joint which properly vents the joint chamber with the external atmosphere while also offering increased resistance to expulsion of grease from the joint chamber, especially during assembly of the CV joint.